Device for shifting products to be dried on a perforated drying drum

ABSTRACT

A device for shifting products to be dried on a perforated drying drum in order to increase the drying efficiency and to prevent the formation of a pattern of the drum holes on the same products, comprises a cylinder, having its longitudinal axis parallel to the axis of the drying drum, at a given distance which is adjustable. Said cylinder can be actuated by a side drive independently of the actuating system of said drum. When the diameter of said cylinder has been chosen, the distance from the drum surface can be varied in order to avoid the increase in the path of the product due the device becoming equal to the center distance between the drum holes or an integral multiple thereof. A plurality of these devices can be advantageously mounted on a drying drum.

United States Patent Garzotto [75] Inventor: Felice Garzotto, Valdagno,Italy [73] Assignee: Rimar S.p.A., Trissino, Vicenza,

Italy [22] Filed: Aug. 16, 1971 21 Appl. No.: 172,009

[30] Foreign Application Priority Data Aug. 22, 1970 Italy 28885 A/70[52] US. Cl. 34/110 [51] Int. Cl. F26g 13/12 [58] Field of Search 34/23,24, 41, 110,

[56] References Cited UNITED STATES PATENTS 3,591,151 7/1971 Kerner34/110 1,564,775 12/1925 Green et a1. 34/110 X 2,440,839 5/1948 Apgar eta1. 34/110 2,788,587 4/1957 Dsenis 34/110 2,532,910 12/1950 Hayward..34/115 Primary Examiner-Charles J. Myhre Assistant ExaminerTheophil W.Streule, Jr. Att0rneyAlvin Browdy and Sheridan Neimark [5 7] ABSTRACT Adevice for shifting products to be dried on a perforated drying drum inorder to increase the drying efficiency and to prevent the formation ofa pattern of the drum holes on the same products, comprises a cylinder,having its longitudinal axis parallel to the axis of the drying drum, ata given distance which is adjustable. Said cylinder can be actuated by aside drive independently of the actuating system of said drum. When thediameter of said cylinder has been chosen, the distance from the drumsurface can be varied in order to avoid the increase in the path of theproduct due the device becoming equal to the center distance between thedrum holes or an integral multiple thereof. A plurality of these devicescan be advantageously mounted on a drying drum.

5 Claims, 4 Drawing Figures PATENIEDJAH 1 w 3,782,003

SHEET 3 0F 3 ARM WITH ARM WITH SQR DRIVING BELT DRIVING BELT CYLINDERSIDES OF THE DRYING,

CHAMBER Fig.5

DEVICE FOR SHIF TING PRODUCTS TO BE DRIED ON A PERFORATED DRYING DRUMBACKGROUND OF THE INVENTION The present invention relates to a deviceadapted to shift a product to be dried, such as fabric pieces, on aperforated drying drum in order to avoid the impressions of the drumholes being left on the product, and to increase the drying efficiency.

It is'known that a fabric of whatsoever type (woven or'non-woven) can bedried by means ofa device which comprises a drum having a suitablediameter, the outer surface thereof being formed by perforated plate ora net provided with a plurality of holes having anypredetermineddiameter and distance between them. The liquid (water or solvents whichmay contain chemicals which are to be left on the fabric to giveparticular features thereto),-which initiallyimpregnates the fabric, isextracted by letting through said holes a flow of air at asuitable'temperature, drawn from the outside into the inside of the drumby a special fan.

It is also known that, this air, passing exclusively through the drumholes and therefore through the fabric approximately at those areaswhich correspond to the regions placed upon the holes, removes from thefabric the liquid (water, solvent etc.) impregnating it. The drying thusbegins by evaporation of the liquid in that areade'finedbyeachindividual hole and continues then in 'the remaining areas with amiscellaneous process which comprises a direct drying ---due to the'heatof the chamber'contain'ing the perforated drum and, what ismoreimportant, a capillary attraction of the liqu'i'd from the areas stillwet or, in any-case, more wet, which are comprised between the holes,towards the less wet or even dry areas corresponding to the holes. Thiscauses such irregularities that the fabric may sometimes be commerciallyunacceptable, both when said drum -.is employed merely to extract theliquids from 'the'fabric, leaving the latter dry and'free from anychemicals, and when such extraction is accomplished inorder to leave onthe fabric some chemicals which have previously and intentionally beenintroduced into the liquid so as to give the fabric some usefulfeatures. lnany case, particularly when, as stated hereinabove, certainchemicals are to be left on the fabric, there occur, during the'drying,migrations ofliquids towards the areas associated with the drum holesand simultaneously therewith migrations of the chemicals contained inthe liquids, thus causing irregularities in the distribution of thesechemicals with a consequent unevenness in the final characteristics ofthe fabric which sometimes carries thereon a clearly visibile pattern ofthe drum holes.

SUMMARY OF THE INVENTION It has now been conceived as an object of thepresent invention a device obviating the above-mentioned drawbacks andwhich allows at the same time an increase in the drying efficiency andtherefore in the output per hour of the fabric dried on the perforateddrum.

It has in fact been observed that during the drying the fabric moveswith the same peripheral speed as the drum, without slipping withrespect to the latter, so that during the whole period of contact theareas of the fabric associated with the perforated areas of the drum arealways the same. On the contrary, if, between the drum surface and thefabric, at one or more locations on the d rum along generating lines ofthe peripheral cylindrical surface of the latter, there are inserteddevices which allow the fabric to be disengaged from the drum and thenimmediately re-engaged on it, the fabric surface which was beforeassociated with the holes will be shifted from its previous position.This may occur one or more times during the period of contact betweenthefabric and the drum in such a way that so high difference of drying inthe same fabric as to allow the abovementioned migrations of chemicalscan never occur.

This provides the substantial advantage that no migration of thechemicals contained, or of the residues still dissolved in the liquidwhich impregnated the fabric occurs, so that these chemicals or residuesare equally distributed in the fabric as they were before be ginning thedrying on the drum, thus avoiding differences on the fabric or even thereproduction of the hole pattern as mentioned above.

The device according to the present invention provides the furtheradvantage that the areas of the fabric overlying the areas between thedrum holeswhere there would be a slower drying with respect to the areasoverlying the holesmove little by little so that they first partiallyand then completely overlie the holes, thus increasing the drying speedand therefore the machine output per unit of time.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects, advantages andfeatures of the device according to the present invention willbeapparent to those skilled in the art upon considering the followingdetailed description of a preferred embodiment given by way of example,in connection with the accompanying drawings, in which:

FIG. 1 shows a perspective view of a conventional perforated dryingdrum;

FIG. 2 shows a cross-section of said drum on which DETAILED DESCRIPTIONOF THE PREFERRED EMBODIMENT Referring now to the drawings and inparticular to FIGS. 1 and 2, there may be seen that during the rotationof the drum 1 actually no relative movement occurs between the sidesurface of the latter and the fabric 2 to be dried thereon. As a resultthose areas of the fabric 2 overlying the holes 3 will perfectlycoincide with these during the whole period of contact the sameoccurring also for those areas of the fabric overlying thenon-perforated regions 4 of the drum 1.

Considering now FIG. 3, there are shown two devices 5 according to thepresent invention, mounted on the drum so that they can vary the path offabric 2 by causing it to slip. The number of devices which can bemounted on the drum ranges from 1 to n, where n is a maximum number suchthat the minimum distance between two devices in succession may stillallow the fabric to contact again the drum under the effect of suctionand other forces which tend to bring it again in such contact position.These devices may be embodied in different ways, the easiest embodimentbeing a cylinder having its axis parallel to the axis of the perforateddrum, at a certain distance from the latter and with a diameter thelower limit of which is given by the possibility of maintainingmechanically said parallelism. The fabric is caused to pass on thecylinder or cylinders 5, slipping from the drum 1, whenever one of thesecylin ders is met, and contacting again the drum when the fabricdescends from such cylinder. The said cylinders can be actuated by meansof a side drive and can be mounted on the machine in such a way that thedistance D, from the perforated drum may be adjusted according to thenature of different fabrics, their flexibility, weight and possibletendency to stretch or generally vary their dimensions.

In the limit case, the cylinder may comprise a simple rod or a wire heldin a suitable position adjustable with respect to the drum, which alsogives excellent results.

Referring now to the FIGS. 3 and 4 there is shown with l the path thatthe fabric 2 would follow along the periphery of the drum 1, were thedevice 5 not present. The real path followed by the fabric 2 on thecylinder 5 is indicated with 1,. Therefore the expression l,l is equalto the increase in the path the fabric must follow and is a function ofthe diameter d of the cylinder 5 and of the adjustable distance D, ofthe latter from the drum surface. It should be avoided that the value 1be equal to the center distance i between the holes (see FIG. 4) or toan integral multiple thereof, as in this case that area of the fabricassociated with a hole 3, after passing the first device 5, would be inthe position 4 (see also FlG. 1) and it would again coincide withanother hole after passing a second device 5 in case that I,I=ni, wheren is an odd integer. The worst case would occur, should it be an evennumber, because then after each device 5 the areas associated with ahole 3 would again overlie each time another hole 3 and so on. To get agradual shifting of the fabric at each device 5, it must be:

where s is a shifting smaller than the hole diameter and the centredistance between the holes, and possibly different from a submultiple ofthese quantities.

In FIG. 4 there is shown an example where s is A; of the hole diameter,or of the centre distance i. In this case the material overlying thearea 4 between the holes after three shiftings will coincide with hole 3and will return in its initial position after six shiftings, which canbe avoided for instance by providing along the perforated drum a smallernumber of devices 5, for instance five. In this way the above formulacan be used to achieve the best results, where the term 1,-! may besuitably varied by adjusting 0,.

Possible additions and/or modifications to the embodiment of the deviceaccording to the present invention as hereinbefore described andillustrated will become apparent to those skilled in the art, withoutdeparting from the scope of the appended claims. In particular itsemployment on perforated drying drums is to be considered exclusively asa particular embodiment, and therefore it is apparent that the deviceaccording to the present invention may be advantageously used in ananalogous way whenever a relative movement between two moving surfacesin contact with each other is desirable.

What I claim is:

1. In a device for drying continuous lengths of products comprising arotating perforated drum having a portion thereof over which the productpasses and means to cause a flow of air therethrough, the improvementcomprising:

cylinder means for increasing the length of the path of travel of theproduct about said drum with respect to the length of said portion ofsaid drum over which the product passes in an amount different from anintegral multiple of the distance between the centers of adjacent holesin said perforated drum, to thereby cause the product to be shifted withrespect to the surface of said drum, said cylinder means comprising atleast one cylinder adjacent to and externally of said drum having awidth substantially coextensive with the width of said drum, the axis ofsaid cylinder being mounted in parallel with the axis of said drum,wherein said cylinder lies between the product and the drum when in use.

2. A device according to claim 1, wherein adjusting means are providedfor adjusting the radial distance of the surface of said cylinder fromthe surface of said drum.

3. A device according to claim 1, wherein said cylinder is actuated by aside drive independently of the actuating system of said drum.

4. A device according to claim 2, wherein as least one of said cylindersis a rod.

5. A device according to claim 2, wherein at least one of said cylindersis a metal wire.

1. In a device for drying continuous lengths of products comprising a rotating perforated drum having a portion thereof over which the product passes and means to cause a flow of air therethrough, the improvement comprising: cylinder means for increasing the length of the path of travel of the produCt about said drum with respect to the length of said portion of said drum over which the product passes in an amount different from an integral multiple of the distance between the centers of adjacent holes in said perforated drum, to thereby cause the product to be shifted with respect to the surface of said drum, said cylinder means comprising at least one cylinder adjacent to and externally of said drum having a width substantially coextensive with the width of said drum, the axis of said cylinder being mounted in parallel with the axis of said drum, wherein said cylinder lies between the product and the drum when in use.
 2. A device according to claim 1, wherein adjusting means are provided for adjusting the radial distance of the surface of said cylinder from the surface of said drum.
 3. A device according to claim 1, wherein said cylinder is actuated by a side drive independently of the actuating system of said drum.
 4. A device according to claim 2, wherein at least one of said cylinders is a rod.
 5. A device according to claim 2, wherein at least one of said cylinders is a metal wire. 